Composite metal strip of an aluminum base bonded to a zinc alloy



Aug. 25, 1970 R. J. RUSSELL ETAL 3,525,598

COMPOSITE METAL STRIP OF AN ALUMINUM BQKSE BONDED TO A ZINC ALLOY Original Filed Dec. 24, 1964 In verztons; Rakert J: Russell,

Zan 011,5 fgif'hiizgiz States Patent-O 3,525,598 COMPOSITE METAL STRIP OF AN ALUMINUM BASE BONDED TO A ZINC ALLOY Robert J. Russell, North Dighton, and Francis T.

Corcoran, North Attleboro, Mass., assignors to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Continuation of application Ser. No. 420,895, Dec. 24,

1964. This application Feb. 6, 1968, Ser. No. 703,482 Int. Cl. B23p 3/00; B321) 15/20 U.S. Cl. 29-1835 2 Claims ABSTRACT OF THE DISCLOSURE A strip material suitable for use in wrap around printing plates is formed of a backing layer of aluminum or aluminum alloy to which is metallurgically bonded a layer of one of the easily etched zinc alloys known as photoengravers zinc.

This case is a continuation of application 420,895 filed Dec. 24, 1964, now abandoned.

This invention relates to composite materials and articles made therefrom. More particularly this invention relates to a composite material and a printing plate formed from a composite material including a layer of easily etchable material bonded to a layer of material having high tensile strength and flexibility.

It is an object of this invention to provide a composite material and an improved printing plate made therefrom which includes a surface which is easily etchable, and which provides a high quality printing surface, and yet which is strong enough to resist creeping, tearing or cracking and yet is flexible enough to permit bending and clamping of the end of the plate in a wrap-around form.

Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction and arrangements of parts, all of which will be exemplified in the structure hereinafter described and the scope of the application of which will be indicated in the appended c aims.

In the accompanying drawings in which one of various possible embodiments of the invention is illustrated:

FIG. 1 is a perspective view of a sheet of composite material according to this invention; and

FIG. 2 is an end view of a printing roller including a wrap-around printing plate formed of the composite material according to this invention.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

Dimensions of certain of the parts as shown in the accompanying drawings have been modified for the purposes of clarity of illustration.

The composite material and printing plate contemplated by this invention is particularly adapted for use in the letter press process of printing. It is also suitable for use in offset printing.

In the letter press process of printing, it is desirable to provide a printing plate capable of being wrapped around the outside of a printing roll and capable of being clamped at its ends. To accomplish this, it is required that the printing plate be a thin, light material, that it be readily etchable, that it give a high quality printing surface and that it have high tensile strength and long wear life on a printing press and that it resist tearing, cracking or creeping.

Various kinds of zinc alloys, known as photoengravers zinc, have desirable etching characteristics in that the top surface of the zinc is not undercut by etching but rather tapers away from the top surface to provide strength in the print plate. In addition, photoengravers zinc etches to a depth that many other materials do not etch to. Finally such material has a fine grain size on the order of 0.016 millimeters which gives desirably high and clear definition to the finished print. However, photoengravers zinc cannot be used in a wrap-around type of printing in other than short runs since it is brittle and weak and tends to tear or crack. In addition, it tends to creep along the sur face of the roll.

Attempts have been made to use a magnesium alloy. While this provides a strength material it does not provide as high a quality printing surface as photoengravers zinc. It has a further disadvantage in that it must be heated and carefully bent before it can be formed into a curved printing plate. Further, the magnesium is subject to edge fracture which makes it undesirable. It has also been proposed to use various types of plastics. However, these materials are highly expensive and further do not provide a high quality printing surface that photoengravers zinc provides. Further, the plastic does not achieve the high degree of fidelity in image that the zinc does. In addition, plastics do not have the wear life that photoengravers zinc possesses, and further, cannot be chrome plated for printing applications, a feature which, as is well known, advantageously improves wear life. Applicants have provided a solution to these problems in this invention.

Turning now to the drawings, particularly FIG. 1, a composite material, generally indicated by reference numeral 10, is formed of a first layer 14 of photoengravers zinc alloy and a second layer 12 of aluminum or an aluminum alloy. Layers 12 and 14 are metallurgically bonded to each other at the molecular level by any suitable bonding method. The zinc comprises approximately of the thickness of composite plate 10 while the aluminum is approximately 40% of the thickness. By way of example, printing plates have been made which are .032 of an inch in thickness.

While there are several zinc alloys known by the name of photoengravers zinc which provide the etching characteristics desirable for printing, the preferred embodiment of applicants material is composed of: .10-.20% by weight of aluminum, .03.05% by weight magnesium; cadmium, iron and lead impurities, none of which exceed .003% each by weight and the balance zinc. This combination provides the optimum alloy for etching characteristics and printing quality and in addition the best alloy for processing that is, bonding to the aluminum layer. The most important additives to the zinc are the aluminum and the magnesium since these serve to refine the grain structure of the zinc and hence provide the finer printing surface characteristics.

The aluminum 14 may be pure aluminum which is selected for strength and ductility or any one of a number of aluminum alloys may be employed so long as they provide the strength needed to withstand the bending and tension of a wrap-around printing plate and resist tearing and cracking as well as creeping.

In one embodiment of applicants material, the aluminum used was aluminum alloy No. 3003. This alloy includes a composition of between .1 and .15 by weight of manganese, a maximum of .6% by weight of silicon, a maximum of .7% by weight of iron, a maximum of .2% by weight of copper, a maximum of .l% by weight of zinc, a maximum of .15% by weight of other metals, and the balance aluminum. This particular alloy provides the best combination of strength and ductility.

There is shown in FIG. 2, a portion of a printing roll employing applicants wrap-around printing plate. 0n the periphery of roll 22 is located a wrap-around printing plate generally indicated by reference numeral 20. Plate 20 is plate 10 wrapped around roll 22 and etched by any one of a number of known etching processes to provide the desired printing surface 32 on the exterior of plate 22. It will be understood that after the printing surface 32 has been etched and cleaned, the surface 32 may be chrome plated to improve the wear life of surface 32.

As also seen in FIG. 2, roller 22 includes an open cavity or recess 24 into which ends 28 of plate extend. Included within recess 24 are gripping or tensioning means 26 which may be of any well known type which can grasp the ends 28 of plate 20 and tension and retain these ends in the recess 24 to hold the plate seen in FIG. 2, the zinc layer 14 is preferably etched away in its entirety from the ends 28 of plate 20. This keeps the zinc from cracking from the surface under the strain of being tensioned and under the strain of the bend through which ends 28 undergo. The flexible and strong aluminum layer withstands the bend of end 28.

It can thus be seen that the objects of the invention are achieved and a composite material suitable for a wrap-around printing plate has been developed which provides both a high quality printing surface and excellent etching characteristics and which is also strong and ductile so that the printing plate does not creep towards one end under the strain of continued printing and which does not crack or fracture at the bend point 28 and which is also capable of extended use in printing without wear. It has been found that printing plates made according to the instant invention have produced more than a million impressions without showing signs of wear when chrome plated.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results are obtained.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense, and it is also intended that the appended claims shall cover all such equivalent variations as come within the true spirit and scope of the invention.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of elements illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

We claim:

1. A printing plate formed of a composite material comprising a first layer of zinc alloy consisting of between .10% and .20% by weight of aluminum, .03%.05% by Weight of magnesium, a maximum of 003% by weight of cadmium, a maximum of 003% by weight of iron, a maximum of 003% by weight of lead and the balance zinc, and a second layer of aluminum alloy consisting of from .1%.5% by weight of manganese, a maximum of .6% by weight of silicon, a maximum of .7% by weight of iron, a maximum of .2% by weight of copper, a maximum of .1% by weight of zinc, a maximum of .15% by weight of other elements and the balance aluminum; the first layer being metallurgically bonded to the second layer and the first layer comprising approximately of the thickness of the composite material.

2. As an article of manufacture, a composite material for use in wrap around printing plates comprising a first layer of easily etched photoengravers zinc alloy including small quantities of aluminum and magnesium to refine the grain structure of the Zinc, said Zinc alloy consisting of between .10% and .20% by weight of aluminum, .03%.05% by weight of magnesium, and a maximum of .003% by Weight of cadmium, a maximum of 003% by weight of iron, a maximum of 003% of lead and the balance zinc, and a second layer of aluminum, said aluminum layer comprising a manganese and silicon containing alloy of aluminum including between .1%-.15% by weight of maganese, a maximum of .6% by weight of silicon, a maximum of .7% by weight of iron, a maximum of .2% by weight of copper, a maximum of .1% by weight of zinc, a maximum of .15 by weight of other elements and the balance aluminum, said first layer being metallurgically bonded to the second layer.

References Cited UNITED STATES PATENTS 1,807,875 6/1921 Robinson 29l97 XR 2,100,255 11/1937 Larson 29l97 2,180,293 11/1939 Finkeldey -1782 2,257,143 9/ 1941 Wood.

2,258,520 10/1941 Somers 75178 XR 1,807,875 6/1931 Robinson 29l97 XR 2,100,255 11/ 1937 Larson 29l97 2,180,293 11/1939 Finkeldey 75178.2

FOREIGN PATENTS 1,362,091 4/1963 France.

HYLAND BIZOT, Primary Examiner US. Cl. X.R. 29l97 

